Continuously variable pulse delay system



Oct. 29, 1957 c. BERKLEY I 2,811,696

CONTINUOUSLY VARIABLE PULSE DELAY SYSTEM Original Filed June 18, 1952INVENTOR CARL BERKLEY OQW QW ATTORNEYS United States PatentfOCONTINUOUSLY VARIABLE PULSE DELAY SYSTEM Carl Berkley, Great Notch, N.J., assignor to Allen B.

Du Mont Laboratories, Inc., Clifton, N. J., a corporation of DelawareOriginal application June 18, 1952, Serial No. 294,290, now Patent No.2,762,984, dated September 11, 1956. Divided and this application July6, 1956, Serial No. 596,343

9 Claims. (Cl. 333--30) This invention relates to a pulse delay systemand more specifically to such a system in which the amount of the pulsedelay is continuously variable over a predetermined range.

It has been customary in producing delayed pulses to employ delay linesusing either lumped or distributed constants. In such an arrangementtaps on the delay line have been provided and connected to a selectorswitch which would thus provide for different fixed amounts of delay.

Another common arrangement employs a long helically wound coil having asliding contact arrangement adapted to contact the individual turns ofthe coil. This latter arrangement has the advantage of enabling a finerdegree of control of the delay introduced since it provides essentiallya tap on each turn of the coil. It has the disadvantage, however, thatthe sliding contact tends to wear the conductor resulting in poorcontact.

My invention contemplates the use of a transmission or delay lineconstructed of saturable material together with means for saturating thesaturable material at any point along the length of the line to therebyprovide a discontinuity and cause reflection of a pulse applied to theline at the point of discontinuity. The reflected pulse appears at theinput to the line, delayed by the time required for the pulse to travelto the discontinuity and be reflected back to the input.

It is an object of my invention to provide a pulse delay system whereinthe amount of delay is continuously variable over a wide range.

It is another object of my invention to provide such a system whichemploys a transmission line of saturable material together with meansfor saturating the material at any point along the line.

It is a further object of my invention to provide a continuouslyvariable pulse delay system while eliminating the use of sliding contactmembers.

Other objects and features of the invention will become apparent whenthe following description is considered in connection with the annexeddrawings, in which,

Figure l is a partly diagrammatic side elevation showing one embodimentof the invention;

Figure 2 represents certain wave forms involved in practicing theinvention;

Figure 3 is a side elevation of a second embodiment of the invention;and

Figure 4 is a transverse cross-sectional view of the device of Figure 3,the section being taken on the plane of the line 44 of Figure 3.

Referring now to the drawings and particularly to Figure 1 there isshown therein an embodiment of my invention in which the transmissionline comprises a long helically wound coil 11 which coil is wound on acore 12 of saturable magnetic material. The coil 11 is surrounded by ashield 13 which may be a shielding braid and is terminated in itscharacteristic impedance 14.

A magnet 15 is mounted for movement longitudinally of the transmissionline and produces a magnetic field 16.

The magnet may be either a permanent magnet or an electromagnet but ineither event serves to produce a discontinuity resulting from thesaturation of the core by the magnetic field. In order that the magnet15 may be positioned at any desired point along the transmission line itis mounted on a carrier such as 17 which is in turn mounted upon thescrew-threaded rod 18. Thus by rotation of the crank 19 the carrier 17may be caused to move along the rod 18 to position the magnet at anydesired point along the transmission line.

It will be clear that pulses which, in the absence of the saturatingmagnetic field will travel to the end of the transmission line and beabsorbed in the terminating resistor without reflection, will, due tothe discontinuity brought about by the presence of the saturating field,be reflected at the point of saturattion and delayed for a time intervalproportioned to the distance from the input to the point of reflection.

The magnetic field may be static thus producing equal delay of pulses ofa sequence or may be dynamic in order to produce pulse time modulationor amplitude modulation.

It may sometimes be preferable to have the lines of force of themagnetic field coincide with the direction of the pulse of signal fieldin the line so that saturation may be produced more readily.

In Figure 2 there has been shown the wave form occurring at the input tothe line as it would appear on an oscillograph. In this figure 21represents a pulse applied to the line and 22 represents the pulsereflected by the discontinuity brought about by the magnetic field. Itwill be obvious that by shifting the position of the magnetic fieldlongitudinally the reflected pulse may be displaced in time from theinput pulse through any interval such as that indicated at 23.

Referring now to Figures 3 and 4, there is shown therein a secondembodiment of the invention in which saturation of a dielectric materialsuch as barium titanate by application of an electrostatic field causesa discontinuity and pulse reflection. In this embodiment thetransmission or delay line comprises a channel member 32 (sometimesreferred to as a slotted line), the channel being substantially filledwith dielectric material 33 which has a conductor 31 centrally locatedtherein. A plate 35 is fixed to an insulating member 36, the member 36being in turn fastened to a carrier 37. Carrier 37 is similar to thatshown in Fig. 1 as 17 and is mounted on a screw-threaded rod 38 whichmay be rotated by the crank 39. This arrangement operates in a mannersimliar to that heretofore described, that is, by rotating the crank 39the carrier nut 37 is caused to move along the rod and the plate 35 thuscaused to move longitudinally along the transmission line. As isindicated in the drawing a high voltage relative to the channel 32 isapplied to the plate 35 and this voltage satruates the dielectric aroundconductor 31 and produces a discontinuity in the line causing reflection'of the pulse as hereinbefore men tioned.

This application is a division of my copending application Serial No.294,290, filed June 18, 1952, now Patent No. 2,762,984, September 11,1956.

While I have described specific embodiments of my invention it will beapparent that many modifications may be made and I wish therefore not tobe limited by the foregoing description, but on the contrary only by theclaims granted to me.

What is claimed is:

l.A continuously variable pulse delay system comprising: a delay linewhich comprises a conductor embedded in a core of saturable dielectricmaterial; means to apply a pulse to one end of said delay line;electrostatic means to saturate a narrow incremental area of saidsaturable dielectric material to produce a pulse refiect-ingdiscontinuity.

2. The device of claim 1 including means to progressively vary theposition of said narrow incremental area.

3. The device of claim 2 including means to terminate the other end ofsaid delay line in its characteristic impedanceh 4. The device of claim3 wherein said saturable dielectric material is barium titanate.

5. A continuously variable pulse delay system comprising: a delay linewhich comprises a conductor embedded in a core of saturable dielectricmaterial, and a U-shaped channel partially surrounding said material;

means to apply a pulse to one end of said delay line; electrostaticmeans to saturate a narrow incremental area of said saturable dielectricmaterial to produce a pulse reflecting discontinuity.

6. {The device of claim 5 wherein said saturati g means comprises a highpotential plate suspended above the open portion of said U-shapedchannel.

7. The device of claim 6 including means to progressively vary theposition of said narrow incremental area.

8. The device of claim 7 including means to termimate the other end ofsaid delay line in its characteristic impedance.

9. A continuously variable delay line which comprises: a pair of inputterminals; a conductor embedded in an electrostatically saturabledielectric material and partially surrounded by a conductive shield;means for applying a saturating electrostatic field to saturate a givennarrow incremental area of said saturable material intermediate the endsthereof; and means for moving said saturating field longitudinally alongsaid conductor, said conductor being connected to one of said inputterminals and said conductive shield being connected to the other ofsaid input terminals.

No references cited. 1

